The goals of our bioorganic chemistry program are to design and synthesize small molecules
and small molecule probes with desired biological activities and understand their
structure activity relationships and target interactions.

We currently have three NIH funded programs. The first program includes the synthesis
and study of enzyme inhibitors in the trehalose utilization pathways of Mycobacterium tuberculosis (Mtb). Mtb is the infectious etiological agent of tuberculosis (TB). Mtb is estimated to infect up to one third of the world’s population, of those people
about eight million develop an active infection. About 1.4 million people die of TB
every year. Further, extensively drug resistant strains of Mtb have emerged making many cases of TB difficult, if not impossible, to treat. Thus,
there is an urgent need to discover small molecule probes that can be used to study
or identify essential enzymes in Mtb. Our studies may lead to therapies to treat TB. Specifically we are discovering and
evaluating new covalent and non-covalent glycoside hydrolase and esterase inhibitors.

A second exploratory program is related to the synthesis of Mtb-active marine natural products which show improved selective activity against non-replicating
Mtb. The new derivatives can also be used to generate chemical probes which will be used
in combination with chemical biology methods for the identification of new biological
targets. These studies are anticipated to be useful for identifying next generation
anti-tubercular agents.

The third program involves the use of antibody recruiting molecules (ARMs) to generate
improved immunotherapeutics. Vaccines can be improved by directing antigens via the
use of ARMs and natural antibodies to antigen presenting cells (APCs). We have used
this approach to improve antibody and T-cell responses against tumor associated-antigens
(TAA) in mice. We are currently working to demonstrate this effect for other antigens
such as bacterial antigen. A second aspect of this program is the development of methods
for vaccine and antigen synthesis.

These programs are highly collaborative and allow students interactions with structural
biologists, microbiologists, immunologists, and natural product experts.

Program 1.Synthesis of chemical probes to investigate enzymes involved in trehalose utilization.

Trehalose is a disaccharide and an essential metabolite found in Mtb. Several enzymes involved in the utilization of trehalose have been found to be essential
to the organism’s survival. We are developing probe molecules which can be used to
understand the detailed molecular interactions that occur between the enzymes involved
in trehalose utilization and their substrates. For example, we are using carbohydrates
as components of substrate analogues and transition state analogues of Mtb Antigen 85s (Ag85s). Ag85s are mycolyl transferases responsible for the synthesis
of the virulence factor trehalose dimycolate (TDM). Ag85s are also involved in mycolation
of carbohydrates on the cell wall. Collectively, this process can be thought of as
mycolyl membrane maintenance. Since Ag85s act on ß-D-arabinofuranoside- and trehalose-based
cell wall structures these carbohydrates are prominent in our inhibitor designs. The
compounds resulting from these investigations are believed to be useful for understanding
key steps in the bacterial cell wall synthesis of Mtb. Since the bacterial cell wall is a well-established target for a number of anti-bacterial
therapies these studies may potentially lead to an improved understanding of cell
wall synthesis targets or to new antibiotics useful for treating the growing threat
of multi-drug resistant Mtb. In addition to Ag85s, we are exploring essential enzymes such as GlgE, a glycoside
hydrolase-like phoshorylase. GlgE is one enzyme responsible for α-glucan synthesis.
It has been reported that absence of GlgE leads to self-poisoning by the accumulation
of phosphosugar maltose-1-phosphate (M1P), directed by a self-amplifying feedback
response leading to cell death. GlgE is essential for survival of the pathogen, and
the absence of a human homologue substantiates GlgE as a new drug target. Figure 1
shows some of the roles of trehalose in Mtb. In addition to these targets we are designing inhibitors against other essential
enzymes in the trehalose utilization pathway. For more information see: http://www.utoledo.edu/offices/marketing/utnews/pdfs/UTnewspdfs/2014.03.17.UTNews.pdf

TB is a tremendous global health threat with nearly 480,000 new cases of multidrug-resistance
TB (MDR-TB)reported in 2015. TB is difficult to treat and control in part due to its
capacity to enter a non-replicating ‘dormant’ state. It is estimated that billons
of individuals harbor a latent Mycobacterium tuberculosis (Mtb) infection, which causes no symptoms and can last a lifetime. One of the most significant
barriers to treating Mtb is the intrinsic drug resistance of dormant bacilli. To overcome this barrier we
are synthesizing new terpenoid-based natural products known to act on dormant Mtb.

Program 3. Targeting APCs to generate improved immunotherapeutics.

Carbohydrates found as naturally occurring glycoconjugates frequently serve as important
markers for cancer and are potential targets for active immune therapy. One example
is the human epithelial type 1 mucin (MUC1), a large polymorphic transmembrane mucin,
expressed on normal glandular epithelia. In cancer cells the MUC1 glycoform distribution
changes to reduced glycosylation with many of the glycan chains truncated relative
to normal cells exposing hidden glycan epitopes on the molecule. Together these aberrant
structures are referred to as tumor-associated antigens (TAAs). Individuals with early
breast cancer who possess natural anti-MUC1 antibodies have been shown to have a reduced
likelihood of distant metastases and better disease-specific survival. We are interested
in synthesizing homogenous MUC1 glycopeptides which contain TAA epitopes. We are also
exploring the use endogenous anti-L-rhamnose antibodies found in humans to augment
immunogenicity of cancer vaccines by introducing antibody recruiting molecules (ARMs)
in to vaccine designs, see Figure 2 for an illustration of the concept. For more information
see: http://utnews.utoledo.edu/index.php/06_02_2011/researchers-integrate-disciplines-to-develop-cancer-vaccines

In addition, we have prepared antigens related to P. aeruginosa Figure 3, a difficult to treat pathogen that is responsible for many hospital acquired
infections and deaths. These antigens along with others are being introduced into
our vaccine platform

Figure 3. Synthesis of a tetrasaccharide component of the lipopolysaccharide of P. aeruginosa.